The invention relates to the field of medical devices and methods used in the treatment of diseases such as cancer which have the ability to metastasize within a patient""s body. More specifically, the invention is directed to methods and devices for accessing sentinel lymph nodes associated with a lesion site within a patient""s body and anchoring devices to these nodes accessed so that they may thereafter be selectively removed and analyzed to determine whether disease has spread from the primary lesion site to the sentinel lymph nodes. In the case of breast cancer patients, such methods and devices may eliminate the need for complete axillary lymph node dissection in patients who do not require such invasive and debilitating procedures.
Metastasis, or migration of cancerous cells, typically occurs through lymph ducts. Sentinel lymph nodes are so-called because, where metastasis occurs, such lymph nodes are often the first locations to harbor metastatic cancer cells. These lymph nodes thus serve as sentinels warning of the spread of the cancerous lesion. A sentinel lymph node may be identified by injection of radioactive material into a primary lesion site such as a cancerous tumor. Detection of radiation at a location other than the injection site indicates that migration of the radioactive material has occurred. The first lymph nodes into which the radioactive material migrates are thus identified as the sentinel lymph nodes.
With regard to breast cancer patients specifically, the determination of the severity of the disease or staging is frequently determined by the level of lymph node involvement in those lymph nodes which correspond to the primary cancer lesion site in the breast. The lymph nodes which correspond to the breast area are typically located in the armpit or axilla of the patient and are connected to the breast tissue of the patient by a series of lymph ducts. Other likely areas for sentinel nodes include inframammary and submammary locations and elsewhere in the patient""s chest. The sentinel lymph nodes can be in fluid communication with other surrounding lymph nodes, however, lymph drainage from the lesion site will first flow to the sentinel lymph nodes. Thereafter, lymph fluid drainage may then continue on to lymph nodes surrounding the sentinel nodes.
Studies have shown that by the time a typical breast cancer lesion reaches the size of 1-2 cm, the cancer will have metastasized to at least one of the sentinel lymph nodes in about one third of patients. Malignant cells break off and drain through the lymph fluid ducts to the lymph nodes and will be apparent in excised lymph nodes if the malignant cells embed in the lymph node. In patients with more advanced disease, the likelihood of spread to sentinel nodes is higher as is the likelihood of spread of the disease to the lymph nodes surrounding the sentinel lymph nodes.
As discussed above, when a tumor lesion is under 1-2 cm, only about ⅓ of patients will have cancer cells in the corresponding lymph nodes, and in the patients where the disease has spread to the lymph nodes, it is often confined to the sentinel lymph nodes.
In the past, a breast cancer patient would normally have a complete axillary lymph node dissection as an adjunct to removal of the primary lesion in the breast. Thus, the patient""s entire lymph node system in the armpit area is removed and biopsied to determine the stage of the cancer and what further treatment was required. However, as discussed above, when the lesion is under 1-2 cm, two thirds of the patients had no migration of cancer cells to the lymph nodes at all, and in others, cancer had only migrated to the sentinel lymph nodes. Thus, total axillary lymph node dissection in two-thirds of the cases were unnecessary. It should be noted that total axillary lymph node dissection can be an extremely painful and debilitating procedure for patients who often suffer from severe lymph edema as a result of the body""s inability to channel the flow of lymph fluid once most or all of the lymph nodes have been excised.
Wires and other devices have been used to anchor devices and to mark suspected cancerous lesion sites within a breast. Such wires may have exposed, sharp ends to cut into tissue, and may expose physicians to accidental injury during excision of tissue. Placement of such marking and anchoring devices is typically performed in the operating room. However, there is a need for methods and devices that can be used to determine the location of sentinel lymph nodes corresponding to a patient""s primary lesion site, in addition to the primary lesion site itself, and a reliable means of accessing the sentinel lymph nodes to determine whether they are involved in the disease. If the sentinel lymph nodes are determined not to have cancer cells within them, then a total axillary lymph node dissection may be avoided. Anchoring devices near to such sentinel nodes would be useful if the sentinel lymph nodes are determined to be involved in the disease.
Radioactive materials have been used as localizing agents which can be injected into the area of a primary lesion to monitor the flow of the materials within the patients body using a variety of detectors. A pharmaceutically-acceptable solution containing a radioactive material may be termed a radiopharmaceutical. Suitable radioactive materials include the radioactive elements Technetium 99, Indium 111, Iodine 123 or Iodine 125.
Although techniques exist to locate the sentinel lymph nodes of a patient with such radiopharmaceutical tagging, what has been needed are methods and devices to precisely access the sentinel lymph nodes of the patient and to anchor a device adjacent sentinel lymph nodes should it be determined that axillary node dissection is necessary.
The invention is directed generally to devices, methods and systems for accessing and anchoring specific target sites within the body of a patient. More specifically, the invention is directed to accessing and anchoring a sentinel lymph node of a patient which corresponds to a lesion site within the patient""s body. The accessing and anchoring device may be used to locate a sentinel lymph node during a surgical procedure in which a sentinel lymph node is surgically removed with the anchor device attached.
The accessing and anchoring device having features of the invention has an elongated shaft, with a tissue cutting member, one or more anchoring elements, and may be configured so that at least a portion of a radiation detector may be disposed at or near the distal end of the shaft to aid in radioactive node location. The anchoring element or elements may extend away from the shaft from a position at or near the distal end of the shaft to form a curved or coiled structure or structures which may extend through at least 180xc2x0, preferably through at least 360xc2x0, and more preferably through at least 540xc2x0. In further embodiments of the invention, there are at least two, and more preferably at least three radially extending anchoring elements, which may extend along a substantial length of the shaft. This substantial length of the shaft may further have an oblong transverse cross section.
The tissue cutting member is configured to cut tissue, having a cutting surface which may have a cutting edge. The tissue cutting member may be an electrode, and in particular may be an electrode with an electrosurgical active surface, which may have a sharp edge. This electrode may be configured to be electrically connected to an RF energy source. The cutting surface of the cutting member is preferably spaced from the distal end of the shaft, and may also have an arcuate shape. The elongated shaft of the accessing and anchoring device may have an inner lumen in which an elongated radiation detector may be slidably disposed to an operative location on the distal section of the shaft to facilitate receiving radioactive emissions from a patient""s node.
Another embodiment of the tissue accessing and anchoring device has an elongated shaft with a distal portion having an oblong transverse cross section. A plurality of anchoring elements extending along the oblong transverse cross-sectional portion of the shaft, preferably in a parallel relationship, and may extend along the long dimension of the oblong transverse cross sectional portion of the shaft.
Detection of radiation in order to identify sentinel lymph nodes may be accomplished by manipulating the shaft and/or the radiation energy detector to detect the amount of radiation energy emanating from the tissue along the longitudinal axis of the shaft, and comparing the amounts of radiation detected from various portions of tissue. Confirmation that the distal end of the shaft is within or adjacent to a sentinel lymph node is indicated by detecting an above-normal amount of radiation energy emanating from the tissue. Such radiation detection is preferably effected with an elongate radiation detector disposed within the inner lumen of the elongated shaft; most preferably, the elongated radiation detector is slidably disposed within the inner lumen of the elongated shaft. A gamma camera, ultrasound imaging, stains, dyes, or skin markings may be used to determine the approximate position of the at least one sentinel lymph node within the patient""s body.
The method of accessing and anchoring a sentinel lymph node of a patient which corresponds to a lesion site within the patient""s body generally includes, first locating the approximate position of a sentinel lymph node that has accumulated radioactive material using a radiation detector; accessing the sentinel lymph node; and then anchoring the node. The node may be accessed by activating the tissue cutting member on the distal end of the device to ablate tissue while passing the shaft into the patient""s body until the distal end of the shaft is disposed within or adjacent to the sentinel lymph node. One or more anchoring elements are extended from the shaft into the sentinel lymph node to secure the distal end of the device to the sentinel lymph node. The step of extending an anchoring element may include a radially extending step, and may further include the step of activating an outer extremity of an anchoring element to emit radiofrequency (RF) energy as it extends. The methods may also include locating a sentinel lymph node using the accessing and anchoring device during a surgical procedure in which a sentinel lymph node is surgically removed with the accessing and anchoring device attached.
The system for accessing and anchoring a sentinel node within a patient includes the previously described accessing and anchoring device with an elongated radiation detecting member slidably disposed within the lumen of the shaft so that radiation detecting elements are located near enough to the distal end of the device to detect radiation emitted from a radioactive sentinel lymph node. The system may further include an electrical lead electrically coupled to a radially extending anchoring member, and another electrical lead electrically coupled to the patient. In this way, RF energy from a RF source can be applied to an anchoring element during its deployment and extension.
The devices, methods and systems of the invention provide the advantages of locating and accessing a desired location within a patient""s body with a single device which may be directly anchored at the location. Including these capabilities in a single device avoids the delay and imprecision in anchoring a device at a proper location that results from the use of multiple devices for these functions. Moreover, the methods and devices of the present invention are suitable for use outside of an operating room, simplifying and reducing the cost of such procedures. In addition, the coiling of the anchoring elements serves to shield the sharp tips, protecting physicians from possible injury during excision of a patient""s tissue. The present invention thus provides improved devices for marking and excising a sentinel lymph node that has accumulated radiation and is suspected of harboring cancerous tissue. In addition, the devices provide anchoring elements that radially extend through a substantial angular extent to provide improved anchoring and demarcation of a location within a patient""s body.
These and other advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying exemplary drawings.